This invention relates to a flame failure device.
The invention provides a flame-failure device comprising:
a heat-resistant, temperature sensitive member to be directly heated by a flame and so arranged that the member will expand or contract along a generally rectilinear axis as it is heated or cooled;
a mount to which one portion of the temperature-sensitive member is connected and relative to which another portion of the temperature-sensitive member will move as the temperature-sensitive member is heated or cooled;
a main valve for controlling supply of fuel to a burner and having a fuel inlet, a fuel outlet, a chamber having a diaphragm defining a wall of the chamber, a main-valve member operatively connected to the diaphragm and movable therewith, and passage means whereby a restricted fuel flow can be supplied to the chamber, and
a pilot valve connected to the chamber of the main valve, having means for venting fuel flowing therethrough from the chamber, for controlling opening and closing of the main valve and having a fixed valve member fixed relative to the mount and a movable valve member movable relative to the fixed valve member and operated by elongate means arranged alongside the temperature sensitive member, the elongate means and movable valve member being arranged to move so as to close the pilot valve when the temperature-sensitive member is heated and to open the pilot valve on cooling of the temperature-sensitive member, the main valve being arranged to open when the pilot valve is closed and to close when the pilot valve is open.
Preferably, the temperature-sensitive device is hollow, tubular configuration and the elongate means is arranged therein.
The elongate means may consist of a single elongate member of non-temperature sensitive material, although, advantageously, comprises a first elongate member of non-temperature sensitive material and a second elongate member between the first elongate member and the movable valve member. Desirably, in this case the second elongate member is of temperature-sensitive material.
Preferably, the temperature-sensitive member has a vent to allow gas entering the pilot valve from the chamber to escape. In a case where the elongate means comprises said first and second elongate members, advantageously the first elongate member is a close sliding fit in the temperature-sensitive member and the vent is nearer than the first elongate member to the fixed valve member.
Preferably, the temperature-sensitive member has an abutment which moves the elongate means on cooling of the temperature-sensitive member. Advantageously, the position of the abutment relative to the fixed valve member is or was at least initially adjustable along said generally rectilinear axis.
Conveniently, said one portion of the temperature-sensitive member is connected to the mount by connecting means which permits or permitted at least initial adjustment of the relative positions of the mount and temperature-sensitive member along said generally rectilinear axis. The connecting means may comprise complementary screw-threads on said one portion of the temperature-sensitive member and the mount. In this case, the abutment may be provided by a deformed zone of said another portion, such as a crimped end, of the temperature-sensitive member.
Alternatively, the abutment is an adjustable screw-threaded member.
The invention also provides an appliance having a main burner and a flame failure device as above described, to provide a flame failure device controlling fuel flow to the main burner.